The 2025 Nobel Prize in Medicine has been awarded to Mary E. Brunkow, Fred Ramsdell, and Dr Shimon Sakaguchi for uncovering how the immune system distinguishes between attacking foreign pathogens and protecting the body’s own cells. Their research identified regulatory T cells, which prevent the immune system from turning against itself, a process known as peripheral immune tolerance.

Sakaguchi discovered the T-cell subtype in 1995, while Brunkow and Ramsdell later linked it to the Foxp3 gene, showing how its mutation causes autoimmune diseases such as Type 1 diabetes and lupus. The findings revolutionized immunology and underpin current efforts to develop therapies that boost immune regulation without weakening defense against infections.

The trio will share about $1.2 million. The Nobel award ceremony takes place in Stockholm on December 10.